CSUN Loc. 444, Las Llajas Canyon (Eocene of the United States)

Where: Ventura County, California (34.3° N, 118.7° W: paleocoordinates 35.1° N, 104.6° W)

• small collection-level geographic resolution

When: Llajas Formation, Lutetian (47.8 - 41.3 Ma)

• The stewart bed is a 1 m thick sandstone unit in the middle of the LLajas formation. Lutetian, chron 21r according to Squires (2001).

• bed-level stratigraphic resolution

Environment/lithology: transition zone or lower shoreface; bioturbated sandstone

• The "Stewart bed" is located in a section of transition from shallow-marine to outer slope and shelf facies. A nearshore environment is interpreted for that portion of the shallow-marine (transgressive) facies which consists of laminated beds alternating with bioturbated beds. In such cases, the finely laminated sand represents storm-influenced stratification, and the biogenic reworking is the inter-storm activity. Shell fragments commonly are concentrated as channel lags in surge channels. Fossils were apparently subjected to wave action because the apices of elongate shells such as Turritella are bimodally oriented in opposite directions. The deeper the water, the less amount of laminated sandstone and the more amount of bioturbated sandstone. Such areas, which were farther below effective wave base, existed 1) where the shallow-marine (transgressive) facies grades into the outer shelf to slope facies and 2) in the shallow-marine (regressive) facies. One of the deepest-water shallow-marine beds was the "Stewart bed."
• sandstone.

Size class: macrofossils

Reposited in the LACM

Collection methods: bulk,

• Repository: Formerly California State University Northridge (CSUN)

Primary reference: R. L. Squires. 1983. New Mollusks from the Lower Middle Eocene Llajas Formation, Southern California. Journal of Paleontology 57(2):354-362 [L. Ivany/E. Kowalski/J. Marcot]more details

Purpose of describing collection: taxonomic analysis

PaleoDB collection 8013: authorized by Linda Ivany, entered by Elizabeth Kowalski on 12.06.2000, edited by Austin Hendy and Jonathan Marcot

Creative Commons license: CC BY (attribution)

Taxonomic list

Polychaeta
 Sabellida - Serpulidae
"Rotularia (Rotularia) tejonensis" = Rotularia (Rotularia) tejonense1
"Rotularia (Rotularia) tejonensis" = Rotularia (Rotularia) tejonense1 Arnold 1909
Cephalopoda
 Nautilida - Nautilidae
Kummelonautilus sp.2 Matsumoto 1984 nautiloid
Scaphopoda
 Dentaliida - Dentaliidae
Dentalium stentor1 Anderson and Hanna 1925 tusk shell
Gastropoda
 Heterostropha - Architectonicidae
 Cerithioidea - Turritellidae
Turritella andersoni1 Dickerson 1916 turret shell
as Turritella andersoni lawsoni
Turritella uvasana1 Conrad 1855 turret shell
as Turritella uvasana applinae
 Architaenioglossa - Ampullinidae
Eocernina hannibali1 Dickerson 1914 snail
Pachycrommium clarki1 Stewart 1927 snail
 Neogastropoda - Fasciolariidae
Clavilithes sp. n. sp. Swainson 1840 snail
 Neogastropoda - Clavatulidae
"Fusiturricula (Crenaturricula) crenatospira" = Crenaturricula crenatospira1
"Fusiturricula (Crenaturricula) crenatospira" = Crenaturricula crenatospira1 Cooper 1894 snail
as Fusiturricula (Crenaturricula) crenatospira domenginica
 Neogastropoda - Turridae
Surculites mathewsonii1 Gabb 1864 turrid
 Neogastropoda - Volutidae
Lyrischapa lajollaensis1 Hanna 1927 volute
 Sorbeoconcha - Strombidae
 Sorbeoconcha - Eocypraeidae
"Cypraea castacensis" = Grovesia castacensis1
"Cypraea castacensis" = Grovesia castacensis1 Stewart 1927 snail
 Sorbeoconcha - Cymatiidae
"Olequahia domenginica" = Ranella domenginica1
"Olequahia domenginica" = Ranella domenginica1 Vokes 1939 snail
 Sorbeoconcha - Cassidae
Phalium (Semicassis) tuberculiformis1, "Galeodea (Caliagaleodea) californica" = Galeodea californica1
"Galeodea (Caliagaleodea) californica" = Galeodea californica1 Clark 1942 snail
 Sorbeoconcha - Ranellidae
Cymatium janetae n. sp. Squires 1983 triton shell
 Sorbeoconcha - Xenophoridae
Xenophora stocki1 Dickerson 1916 carrier shell
Bivalvia
 Pectinida - Pectinoidae
Spondylus carlosensis1 Anderson 1905 scallop
 Ostreida - Ostreidae
"Ostrea idriaensis" = Acutostrea idriaensis1
"Ostrea idriaensis" = Acutostrea idriaensis1 Gabb 1869 oyster
 Arcida - Glycymerididae
 Cardiida - Cardiidae
"Nemocardium linteum" = Nemocardium (Nemocardium) linteum1
"Nemocardium linteum" = Nemocardium (Nemocardium) linteum1 Conrad 1855 cockle
 Pholadida - Teredinidae
? Teredo sp.1 Linnaeus 1758 clam
 Solenida - Solenidae
"Solena (Eosolen) navacularis" = Solena (Eosolen) novacularis1
"Solena (Eosolen) navacularis" = Solena (Eosolen) novacularis1 Anderson and Hanna 1925 clam
 Carditida - Crassatellidae
Crassatella uvasana1 Conrad 1855 clam
Anthozoa
 Scleractinia - Caryophylliidae
? Trochocyathus striatus1 Gabb 1864 stony coral